Consider using 'local' as the default Asymptote method

[sean-fitzpatrick]

The sample book created using pretext-new-book contains an Asymptote image, and soon the same will likely be true of the sample slideshow. (This is an issue opened by @rbeezer on the pretext repo.)

As we saw during Oscar's getting started demo in Ohio, the Asymptote build failed.

Unfortunately, there have been some reliability issues with the server method. (It seems that whenever the Asymptote web interface is updated, our ability to use it from the command line breaks.)

The original motivation for using the server method was that support for things like 3D WebGL output was new, and people with older Asymptote versions were not able to use the new features.

But this support is now at least 5 years old. Anyone who is able to build TikZ images will also be able to build Asymptote, since it is bundled with any LaTeX distribution. (If it is not already in the codespaces environment, it should be easy to add.)

Building using a local asy binary would ensure that the Asymptote samples in our examples do not cause a failed build.